[Shanghai University of Technology] Simple electronic load + Wu Yanpu

1. Function introduction

This work uses the INA219 power module to read the voltage and current passing through the load, and calculate the power and equivalent resistance of the load. In constant current mode, this work uses two TIP41CA transistors as power components to adjust the load current through a 10k coarse adjustment potentiometer, a 200 ohm fine adjustment potentiometer and a 220 ohm fixed value resistor at the base terminal. When all potentials When the potentiometer is at the maximum value, the current is 30MA, and when the potentiometers are at the minimum value, the current is 1400MA. In constant resistance mode, this work uses a 10k potentiometer and a 220 ohm 1W fixed value resistor to achieve constant resistance. TIP41CA can measure the resistance value at this time.

In addition to the constant current and constant resistance mode, this work can also measure the load regulation rate. After pressing the "Mode Select" button, the OLED display switches to the load regulation rate display page, adjust the constant current value to the minimum, and then press the "Load Regulation Rate" Press "Calculate" button. At this time, Arduino records the current voltage value as the reference voltage, and calculates the proportion of voltage drop after increasing the current. In addition, this work uses a 5V relay to realize the overvoltage protection function, and a one-bit DIP switch to realize the open circuit setting in constant current mode.

2. Picture display

constant current mode

constant resistance mode

Calculate load change rate

Overvoltage protection

3. Procedure

See project attachments for details

The main program is in AD.ino

The OLED library is at Adafruit_ssd1306syp.zip

The INA219 library is in Adafruit_INA219-master.zip